Originally Posted by
Glowgeek
The proprietary Saito gas carbs, sans the early FG-20 version, run spectacularly. I have three FG-21 and an FG14. One of the FG-21 has about 3 gallons run through and the oil comes out almost completely clear with no visible smoke except upon acceleration from a prolonged idle.
A good friend of mine has an FG-41TS with about 1 gallon run through. He says the exhaust oil is getting clearer each time he runs it. According to him the engine runs terrific but he is out of state so I'm taking his word on it.
John, my FG carbs do have a button with a spring in the middle of the carb. I assume this is for returning the pump diaphrams due to the lack of positive pulse pressure. It does not appear to seal anything. The pump diaphram has reed/flap valves like a Walbro. The FG-41TS carb appears to be same as used on the FG-21 albeit having a different part number. I searched for a carb rebuild kit for the 41TS to see if it used the same parts as a 21 but no luck finding one yet.
Right, the pump diaphragm has the return spring on one side of the diaphram, along with the flapper check valves, that's part of the pump section to draw fuel from the tank to feed the metering section... the pump pulse is ported internally through the venturi throat... where it differes greatly from the walbro, if you look at the carb exploded view in the 41ts pdf, you'll see the 4 button / disc valves between each of the fuel metering stages... from what I gather, those button/ disc valves come as part of the complete carb assembly, or as part of the fuel pump subassembly... they function similar to the walbro needle & seat... when those button valves start to leak, fuel will drip from the venturi and the engine will run erratic, not hold a tune.